From the book jacket:
Darmentraea became a prison, Galaseya a thriving utopia; Diraetus finally found peace, and Heirsha provided healing to all. Amber and her friends had adjusted to their new roles in life, when an unexpected surprise appeared on Heirsha—a secret truth. One that could shed light on the mysteries surrounding the immortal families.
Why so much bitterness? What happened between Jermiar and Huntinylar? What secrets does Marsacor conceal behind his course exterior? Who is the mysterious family member that no one seems to want to talk about? And why were both families plagued by constant tragedy? One answer—Khyra Crawford.
Amber Oak's story gets even more detailed in this imaginative prequel from author Ceara Comeau. Years before the events of Memories of Chronosalis, Kyhra Crawford rebels against her industrialist father's demanding ways and slip-shop production practices. Determined to stop the pollution that her father is producing, Khyra joins an underground research team, dedicated to saving the planet. When a deadly virus wipes out most of earth's population, it seems the human race is doomed - until Kyhra's old friend reappears with a bold - and risky - plan. But even if they save the human race, can Krhra and her rag-tag team of unlikely allies save humanity from an even more insidious evil? Remorse is a galaxy spanning adventure with a spunky lead - though listed as prequel, it is definitely best read after Memories of Chronosalis.